In trading, where risk includes, you can predict the movements of the market with a basis (theoretical). In gambling, you can predict without a basis, pure guess. We shouldn't take the terms literally, it'll gonna misinterpret the whole definition.
eg.
Standard deviation can be used on graphs and it's also considered as a prediction, it means risk is the right term to be used since we can predict the outcome through a mathematical solution(basis).
If we give an example to trading, once we see an oversold or overbought on a certain price level, we can determine the next possible price movement because of the indicators. Still a prediction or guess.
If we give an example to sports betting, once we look at both team status, either injury update, homecourt advantage, past performance, we can determine who will win. And the same as above, still as a prediction or guess.
The bottom line, both rely on analysis. Even with a strong basis, it can be spoiled. Both have different factors to look at
e.g trading=chart; sports betting=status, past performance, etc. I'm a pure sports bettor gambler for years and I don't believe in guesses just to win. It can't be applied in sports betting or strategy-based games
e.g card games, PVP, E-sports. Like trading, it needs analysis.
Both gambling and trading have risks. It's a dumb move just to place bets on gambling because we are guessing. The same goes for trading.
However, my statement can't be applied to those gambling games that deal with the house-edge. Maybe those are the ones you are pointing here and not gambling in general?